Efficient synthesis of functionalized alkylidenephthalides, butenolides, pyranones, and isocoumarins <i>via</i> I ₂ –PPh ₃ : synthesis of Thunberginols A and F

A simple and efficient synthesis of functionalized alkylidenephthalides, butenolides, pyranones, and isocoumarins was achieved using I₂-PPh₃-Et₃N reagent combination. The products obtained through this method act as versatile components in organic synthesis, enabling further modifications of functional groups. This method exhibits a wide substrate scope, employs straightforward and cost-effective reagents, eliminates the need for acidic, carbodiimide or other coupling agents, and operates at ambient temperature. Moreover, this methodology has been successfully applied to the synthesis of two natural products, Thunberginols A and F.